This invention relates to thin-film electroluminescent devices (TFEL) and, more particularly, to a TFEL matrix display panel utilizing different color phosphor materials in separate layers to provide a multi-colored display.
AC-driven monochromatic TFEL devices, such as that depicted in Inazaki et al Pat. No. 3,946,371 comprising five layers, namely, a pair of insulating layers sandwiching an electroluminescent phosphor layer, and a pair of electrodes in turn sandwiching the insulating layers, with the entire laminar structure being supported on a substrate of glass or other transparent material, are well known. Such TFEL devices, with associated power supply, matrix addressing and logic circuitry, are utilized as flat screen display monitors for portable computers in military and commercial applications. However, it is desirable, particularly for the purposes of improving the legibility and usefulness of such display devices, to have the information presented in more than one color. At the present time multi-color display capability in computers is provided principally by color CRT devices but it would be desirable, particularly in applications requiring portability and lightweight, that a flat screen display be available with this capability as well.
While full spectrum color display would require three primary color generation capability in a display device, a very useful range and variety of color discrimination is obtainable by the device of the present invention utilizing two different color phosphors.